Measurement of hemoglobin within blood helps to diagnose and manage a number of conditions, but this requires either blood draws or expensive pulse oximeters.

Researchers of the University of Washington developed an app called HemaApp that uses the phone’s built-in light and camera to detect the color intensity of blood passing through a finger. The user simply places a finger over the camera lens, making a solid contact, and runs the app to do its thing. The app turns on the nearby LED light, which shines light through the finger, and uses the camera to detect specific features that point to the amount of hemoglobin.